Where has Luke Skywalker been?
This question is asking "Do we have any evidence of where he's been?"
Which is a cut and dried objective Yes/No no question, but it was closed as "primarily opinion based".
Either the answer is "Yes (and here's where)" or "No (and hopefully an explanation)".
If it were closed due to our future works policy, that seems to be a misinterpretation. This question isn't (and never was, if you look at the edit history) asking about the content of a work that's not yet released. It's present tense asking if, up to this point in time, has any info been released.
Our future works policy was intended to stop questions being asked specifically about works that haven't been officially released yet. An example would be "What is Luke Skywalker's role in Episode VIII?"
Furthermore, it was closed after it was answered, and the answer clearly shows that there is (and always was) an objective answer.